N-(Arylsulfonyl)-2-nitro-2-(tetrahydro-2H-1,3-thiazin-2-ylidene)acetamides

ABSTRACT

Novel compounds, identified in the title, useful as insecticides.

DESCRIPTION OF THE INVENTION

It has been found that useful insecticidal activity is possessed by N-(arylsulfonyl)-2-nitro-2-(tetrahydro-2H-1,3-thiazin-2-ylidene)acetamides. These compounds are described by the formula: ##STR1## wherein R is hydrogen or middle halogen-- i.e., chlorine or bromine-- and R¹ is phenyl or phenyl substituted by from one to two of one or more of halogen, nitro, cyano, alkyl or alkoxy of from one to six carbon atoms or phenoxy. Preferably, any halogen on the phenyl ring also is middle halogen.

Because of their insecticidal activity characteristics, a preferred subclass of the genus of the invention consists of those compounds of formula (I) wherein R is hydrogen.

For illustration, preparation of typical species of the genus is described in the examples included hereinafter. Other typical, illustrative species of this genus include those wherein the symbols represent the following moieties, this manner of naming these species being accurate, yet pointing out the differences between the different species more clearly than if the entire, complicated name of each species were to be given:

    ______________________________________                                         R = H,       R.sup.1 =                                                                              4-chlorophenyl                                                                 2-fluorophenyl                                                                 phenyl                                                                         3-methylphenyl                                                                 4-bromophenyl                                                                  2-chlorophenyl                                                                 3-chlorophenyl                                                                 4-fluorophenyl                                                                 4-cyanophenyl                                                                  2,5-dichlorophenyl                                                             2,5-dimethylphenyl                                                             2-ethoxyphenyl                                                                 4-ethoxyphenyl                                                                 3-methoxyphenyl                                                                4-methoxyphenyl                                                                2-nitrophenyl                                                                  3-nitrophenyl                                                                  4-nitrophenyl                                                                  2-methylphenyl                                                                 4-methylphenyl                                                                 3-phenoxyphenyl                                                                3,4-dichlorophenyl                                        R = Cl,      R.sup.1 =                                                                              phenyl                                                                         4-chlorophenyl                                                                 4-bromophenyl                                                                  4-fluorophenyl                                                                 4-cyanophenyl                                                                  2,5-dichlorophenyl                                                             2,5-dimethylphenyl                                                             2-ethoxyphenyl                                                                 3-methoxyphenyl                                                                2-nitrophenyl                                                                  4-nitrophenyl                                                                  4-methylphenyl                                                                 3-phenoxyphenyl                                           R = Br,      R.sup.1 =                                                                              2-fluorophenyl                                                                 phenyl                                                                         3-methylphenyl                                                                 2-chlorophenyl                                                                 3-chlorophenyl                                                                 2,5-dichlorophenyl                                                             2,5-dimethylphenyl                                                             4-ethoxyphenyl                                                                 4-methoxyphenyl                                                                3-nitrophenyl                                                                  2-methylphenyl                                                                 3,4-dichlorophenyl                                        ______________________________________                                    

Compounds of this invention wherein R is hydrogen can be prepared by treating tetrahydro-2-(nitromethylene)-2H-1,3-thiazine with an equimolar quantity of the appropriate arylsulfonyl isocyanate. Suitably, a solution of the isocyanate in a lower haloalkane is added slowly to a stirred solution or solution/suspension of the thiazine in a solvent such as a mixture of an ether and a lower haloalkane, at a temperature of from about 15° C. to about 40° C. The thiazine precursor can be prepared by treating 5,6-dihydro-2-(methylthio)-4H-1,3-thiazine (A. F. McKay et al., J. Am. Chem. Soc., 80, 3339 (1958)) with an alkyl nitroacetate (S. Zen, et al., Kogyo Kagaku Zasshi, 74, 70 (1971)) in the presence of a catalytic amount of zinc ion (e.g., zinc chloride) to form the alkyl nitro(tetrahydro-2H-1,3-thiazine-2-ylidene)acetate, which is hydrolyzed with a base and decarboxylated by acidification to give the thiazine. The arylsulfonyl isocyanates contemplated as precursors for compounds of this invention are a known class of compounds, as shown in the article by Henri Ulrich, "The Chemistry of Sulfonyl Isocyanates", Chemical Reviews, Vol. 65, pp. 369-376 (1965), and in U.S. Pat. Nos. 3,799,758 and 3,371,114. Compounds of this invention wherein R is chlorine or bromine, respectively, can be prepared by treating the appropriate compound of this invention wherein R is hydrogen with N-chloro- and N-bromosuccinimide, respectively. The halogenation is conveniently effected by treating a solution of the thiazine (R= H) in a lower haloalkane with an equimolar quantity of the succinimide, at a temperature within the range of from about 10° C. to about 40° C. The desired product, in each case, can be isolated from the crude reaction mixture and purified by conventional methods, such as filtration, extraction, crystallization and elution (chromatography). Techniques for conducting these treatments are exemplified in Examples 1 and 2, following.

Procedures for preparing compounds of this invention are illustrated in the following examples of the preparation of particular species thereof. In all cases, the identity of the product, and the identity of any intermediate involved were confirmed by appropriate analysis:

EXAMPLE 1 N-((4-methylphenyl)sulfonyl)-2-nitro-2-(tetrahydro-2H-1,3-thiazin-2-ylidine)acetamide (1)

To a mixture of 235 g of 5,6-dihydro-2-(methylthio)-4H-1,3-thiazine and 2 g of zinc chloride at approximately 115° in a nitrogen atmosphere, 263 g of ethyl nitroacetate was added dropwise over a 1.5 hour period. The mixture was held at 110°-120°. When evolution of methyl mercaptan ceased after 45 minutes further stirring of the heated mixture, 1 g of zinc chloride was added and the mixture was stirred at about 115° for 1.25 hours. An additional 1 g of zinc chloride then was added and stirring of the mixture at about 115° was continued for 1.5 hours. The mixture then was poured into a cooled solution of 2/1 ether/isopropyl alcohol mixture. The crystallized product was collected, washed with ether and dried under reduced pressure to leave a tan solid, m.p. 100°-102°, which on recrystallization from methanol gave ethyl nitro(tetrahydro-2H-1,3-thiazin-2-ylidene)acetate (1A) as a pale yellow solid, m.p. 105°-106°.

2.3 g of 1A was added to 10 ml of 20% aqueous sodium hydroxide and the mixture was stirred at room temperature for 12 hours. The resulting solution was treated dropwise with 3.5 g of acetic acid. The addition was accompanied by vigorous gas evolution. The resulting mixture was extracted with methylene chloride and the extract was dried (magnesium sulfate) and concentrated under reduced pressure to give tetrahydro-2-(nitromethylene)-2H-1,3-thiazine (1B) as a pale yellow solid, m.p. 76°-78°.

A solution of 5 g of p-toluenesulfonyl isocyanate in 10 ml of methylene chloride was added dropwise at 26°-29° to a mixture of 4.0 g of 1B, 40 ml of ether and 10 ml of methylene chloride. The resulting mixture was stirred for one hour. Solid product was recovered by filtering the mixture, washing it well with ether and air drying. The solid was dissolved in 100 ml of methylene chloride. The solution was treated with Norite, filtered and concentrated to dryness. The resulting solid was crushed under ether, washed with ether and dried to give 1, as a white solid, m.p.: 137°-138°.

Example 2 2-(3-chlorotetrahydro-2H-1,3-thiazin-2-ylidene)-N-((4-methylphenylsulfonyl)-2-nitroacetamide (2)

A mixture of 3.6 g of 1 and 1.4 g of N-chlorosuccinimide suspended in 50 ml of carbon tetrachloride was stirred for 4.5 at room temperature. Solid product was collected and dissolved in methylene chloride. The solution was washed with water. The organic phase was charcoaled and dried to give a liquid, which on crystallization from ether gave 2 as a light tan solid, m.p.: 107°-110°.

Compounds of this invention are of particular interest for control of the larvae ("caterpillar" or "worm" forms) of insects of the genus Heliothis, such as H. zea (corn earworm, cotton bollworm, tomato fruitworm), H. virescens (tobacco budworm), houseflies and aphids. In tests that have been conducted, Compounds 1 and 2, representative compounds of the invention, have exhibited substantial activity with respect to houseflies, pea aphids and larvae of the corn earworm but low, or no, toxicity to other insects, such as the 2-spotted spider mite and mosquito larva.

Activity of Compounds 1 and 2 with respect to insects was determined by establishing the LC₅₀ dosage (in milligrams of test compound per 100 milliliters of solvent required in the solution or suspension of test compound used as a spray) to kill 50% of the test insects. The liquid carrier was composed of 2 parts by weight of acetone, 8 parts by volume of water and 0.05 parts by weight of Atlox 1045A, a wetting agent. The test insects were the housefly, corn earworm, mosquito, pea aphid and 2-spotted spider mite. Activity with respect to mosquito larvae was determined by placing the larvae in water containing the test compound.

The invention includes within its scope insecticidal compositions comprising an adjuvant-- that is, a carrier, optionally a surface-active agent-- and, as active ingredient, at least one insecticide of this invention. Likewise the invention includes also a method of combatting insect pests at a locus which comprises applying to the locus an effective amount of at least one insecticide of the invention.

The term "carrier" as used herein means a material, which may be inorganic or organic and of synthetic or natural origin, with which the active compound is mixed or formulated to facilitate its application to the plant, seed, soil and other object to be treated, or its storage, transport or handling. The carrier may be a solid or a liquid.

Suitable solid carriers may be natural and synthetic clays and silicates, for example, natural silicas such as diatomaceous earths; magnesium silicates, for example, talcs; magnesium aluminum silicates, for example, attapulgites and vermiculites; aluminum silicates, for example, kaolinites, montmorillonites and micas; calcium carbonate; calcium sulfate; synthetic hydrated silicon oxides and synthetic calcium or aluminum silicates; elements such as for example, carbon and sulfur; natural and synthetic resins such as, for example, coumarone resins, polyvinyl chloride and styrene polymers and copolymers; solid polychlorophenols; bitumen, waxes such as beeswax, paraffin wax, and chlorinated mineral waxes; degradable organic solids, such as ground corn cobs and walnut shells; and solid fertilizers, for example, superphosphates.

Suitable liquid carriers include solvents for the compounds of this invention and liquids in which the toxicant is insoluble or only slightly soluble.

Examples of such solvents and liquid carriers generally are alcohols, for example, isopropyl alcohol, ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic hydrocarbons such as benzene, toluene and xylene; petroleum fractions such as kerosene, light mineral oils, chlorinated hydrocarbons, such as carbon tetrachloride, perchlorethylene, trichloroethane, including liquefied normally vaporous gaseous compounds. Mixtures of different liquids are often suitable.

If used, the surface-active agent may be an emulsifying agent or a dispersing agent or a wetting agent. It may be nonionic or ionic. Surface-active agents usually applied in formulating pesticides may be used. Examples of such surface-active agents are the sodium or calcium salts of polyacrylic acids and lignin sulfonic acids; the condensation products of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; fatty acid salts of low molecular weight mono-, di- and trialkylamines; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohols or alkyl phenols for example, p-octylphenol or p-octylcresol, with ethylene oxide and/or propylene oxide; sulfates or sulfonates of these condensation products; alkali or alkaline earth metal salts, preferably sodium salts, of sulfuric or sulfonic acids esters containing at least 10 carbon atoms in the molecule, for example, sodium lauryl sulfate, sodium secondary alkyl sulfates, sodium salts of sulfonated castor oil, and sodium alkylaryl sulfonates such as sodium dodecylbenzene sulfonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The compositions of the invention may be formulated as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates or aerosols. Encapsulated formulations and controlled release formulations also are contemplated, as are bait formulations. Wettable powders are usually compounded to contain 25, 50 or 75%w of toxicant and usually contain, in addition to solid carrier, 3-10%w of a dispersing agent and, where necessary, up to 10%w of stabilizer(s) and/or other additives such as penetrants or stickers. Dusts are usually formulated as a dust concentrate having a similar composition to that of a wettable powder but without a dispersant, and are diluted in the field with further solid carrier to give a composition usually containing 1/2-10%w of toxicant. Granules may be manufactured by agglomeration or impregnation techniques. Generally, granules will contain 1/2-25%w toxicant and 0-10%w of additives such as stablizers, slow release modifiers and binding agents. Emulsifiable concentrates usually contain, in addition to the solvent, and when necessary, co-solvent, 10-50%w/v toxicant, 2-20%w/v emulsifiers and 0-20%w/v of appropriate additives such as stabilizers, penetrants and corrosion inhibitors. Suspension concentrates are compounded so as to obtain a stable, non-sedimenting, flowable product and usually contain 10-75%w toxicant, 0-5%w of dispersing agents, 0.1- 10%w of suspending agents such as protective colloids and thixotropic agents, 0-10%w of appropriate additives such as defoamers, corrosion inhibitors, stabilizers, penetrants and stickers, and as carrier, water or an organic liquid in which the toxicant is substantially insoluble; certain organic additives or inorganic salts may be dissolved in the carrier to assist in preventing sedimentation or as antifreeze agents for water.

Aqueous dispersions and emulsions, for example, compositions obtained by diluting a wettable powder or an emulsifiable concentrate according to the invention with water, also lie within the scope of the present invention.

The compositions of the invention may also contain other ingredients, for example, other compounds possessing pesticidal, herbicidal or fungicidal properties, or attractants, such as pheromones, attractive food ingredients, and the like, for use in baits and trap formulations.

These compositions are applied in sufficient amount to supply the effective dosage of toxicant at the locus to be protected. This dosage is dependent upon many factors, including the carrier employed, the method and conditions of application, whether the formulation is present at the locus in the form of an aerosol, or as a film, or as discrete particles, the thickness of film or size of particles, the insect species to be controlled and the like, proper consideration and resolution of these factors to provide the necessary dosage of active material at the locus being within the skill of those versed in the art. In general, however, the effective dosage of toxicants of this invention at the locus to be protected-- i.e. the dosage to which the insect contacts-- is of the order of 0.001 to 0.5% based on the total weight of the formulation, though under some circumstances the effective concentration will be as little as 0.0001 or as much as 2%, on the same basis. 

I claim:
 1. A compound of the formula: ##STR2## wherein R is hydrogen or middle halogen and R¹ is phenyl or phenyl substituted by from one to two of one or more of halogen, nitro, cyano, alkyl or alkoxy of from one to six carbon atoms or phenoxy.
 2. A compound according to claim 1 wherein R is hydrogen.
 3. A compound according to claim 2 wherein R¹ is 4-methylphenyl.
 4. An insecticidal composition comprising an insecticidal amount of a compound according to claim 1, together with a carrier, and optionally a surface-active agent.
 5. A method for killing houseflies, aphids and insects of the genus Heliothis which comprises contacting them with a lethal amount of a compound defined in claim
 1. 